(a) Field of the Invention
This invention relates to novel 1,2,3,4-tetrahydropyrrolo(1,2-a)pyrazine derivatives, to therapeutically acceptable acid addition salts thereof, to processes for their preparation and to pharmaceutical compositions of the derivatives.
More specifically, the present invention relates to novel 1,2,3,4-tetrahydropyrrolo(1,2-a)pyrazine derivatives having a substituent at position 1 and optionally further substituted at position 2. These derivatives are useful as antidepressant agents.
(b) Description of the Prior Art
A number of compounds having a pyrrolo(1,2-a)pyrazine nucleus have been reported. For example, 1-methylpyrrolo(1,2-a)pyrazine is described by W. Herz and S. Tocker, J. Amer. Chem. Soc., 77 6355(1955). 1-Methyl-3,4-dihydropyrrolo(1,2-a)pyrazine as well as substituted pyrrolo(1,2-a)pyrazine derivatives are reported by I. Flament et al., Helv. Chim. Acta, 60, 1872(1977), see also A. P. Dunlop and S. Swadesh, U.S. Pat. No. 2,655,512, issued Oct. 13, 1953.